Evidence that the C4 pathway is built on existing gene networks in C3 plants

Steven Burgess from the Hibberd lab is first author on a paper in Nature Plants that sheds light on factors facilitating the repeated evolution of C4 photosynthesis. Previously, our understanding of C4 evolution was that genes of the C4 cycle have to mutate to become part of the photosynthesis network in C4 plants. In this work, we show that this is not the case, but rather that these genes are already regulated by light and the chloroplast in the ancestral C3 state. The molecular changes to gene expression therefore require an amplification of pre-existing responses rather than evolution of new ones.